You did not post your code in full, so it's difficult to say exactly.
In case the input record is really RECFM=VB, as stated by your INREC statement:

Code:

. . . . BUILD=(1,4,
5:%01,JFY=(SHIFT=LEFT), . . . .

and also your output dataset is RECFM=VB, then conversion FTOV has no meaning; it always caused SYNSORT error message in my experience.

You said you tried "to avoid copying of RDW from input record to the output one", but it seems to me that instead of that, you make even more senseless conversion between VB-->FB-->VB, for no reason. Cannot say without you code in full.

Besides of those hidden parts of your code, it always makes sense to place your statements in the order they are actually applied/executed, for not to create additional mess in readers' mind: